package org.brownflat.dbinit.upgrade;

import org.apache.log4j.Logger;

import java.io.File;
import java.io.IOException;
import java.net.URL;
import java.util.ArrayList;
import java.util.Enumeration;
import java.util.List;

/**
 * <p>Database Init &copy Rupert Jones 2013</p>
 *
 * @author rup
 */
public class UpgradeClassFinder implements UpgradeFinder {
    private final static Logger LOG = Logger.getLogger(UpgradeClassFinder.class);

    public Object[] find(String packageName, String pattern) {

        ArrayList<Class> classes = new ArrayList<Class>();
        try {
            ClassLoader classLoader = Thread.currentThread().getContextClassLoader();
            assert classLoader != null;
            String path = packageName.replace('.', '/');
            Enumeration<URL> resources = classLoader.getResources(path);
            List<File> dirs = new ArrayList<File>();
            while (resources.hasMoreElements()) {
                URL resource = resources.nextElement();
                dirs.add(new File(resource.getFile()));
            }

            for (File directory : dirs) {
                classes.addAll(findClasses(directory, packageName));
            }
            return classes.toArray(new Class[classes.size()]);
        } catch (ClassNotFoundException cnfe) {
            LOG.error(cnfe);
        } catch (IOException e) {
            LOG.error(e);
        }
        return classes.toArray();
    }

    /**
    * Recursive method used to find all classes in a given directory and subdirs.
    *
    * @param directory   The base directory
    * @param packageName The package name for classes found inside the base directory
    * @return The classes
    * @throws ClassNotFoundException
    */
    private List<Class<Upgrade>> findClasses(File directory, String packageName) throws ClassNotFoundException {
        List<Class<Upgrade>> classes = new ArrayList<Class<Upgrade>>();
        if (!directory.exists()) {
            return classes;
        }
        File[] files = directory.listFiles();
        for (File file : files) {
            if (file.isDirectory()) {
                assert !file.getName().contains(".");
                classes.addAll(findClasses(file, packageName + "." + file.getName()));
            } else if (file.getName().endsWith(".class")) {
                Class clazz = Class.forName(packageName + '.' + file.getName().substring(0, file.getName().length() - 6));
                boolean assignableFrom = Upgrade.class.isAssignableFrom(clazz);
                if(assignableFrom) {
                    classes.add(clazz);
                }
            }
        }
        return classes;
    }
}
